Advanced 3D Printing

The Prusa Pro HT90 is not a faster version of the Prusa MK4S. It is a different machine for a different purpose — built around one capability that almost no desktop 3D printer offers: a fully enclosed chamber that heats to 90°C. This article explains what that means in practice, who the machine is designed for, and how it compares to the alternatives. The Problem with Engineering Materials on Standard Desktop Printers If you've ever tried to print PEEK, PA-CF, or even ABS reliably on a standard open-frame FDM printer, you'll know the frustration. Surface delamination. Warping that lifts corners off the bed mid-print. Internal stresses that cause parts to crack under load days after printing. These aren't settings problems. They're physics problems. High-performance engineering polymers crystallise — they form ordered molecular structures as they solidify. That process requires controlled, gradual cooling. When a part is being printed in an open environment at room temperature, the layers that have already been deposited cool too fast and too unevenly. The result is thermal stress, poor interlayer adhesion, and warping. The material is fighting the printing process. The solution is an enclosed, heated build chamber. Keep the ambient temperature around the part high enough throughout the print, and the material cools gradually and uniformly. Crystallisation happens correctly. Layers bond properly. The part comes out the way it was designed. This is exactly what the Prusa Pro HT90 provides. Its fully enclosed chamber heats to 90°C — high enough to enable reliable printing with the most demanding engineering polymers on the market. What Makes the HT90 Different A number of desktop printers now offer enclosed chambers — the Bambu Lab X1C being the most prominent. But most of these have passive enclosures or active heating capped at around 50–60°C. At that temperature range, you can improve ABS and ASA results meaningfully. You cannot reliably print PEEK or Ultem. 90°C is the threshold that matters for true high-performance polymer processing. At 90°C ambient chamber temperature, combined with a nozzle capable of reaching 500°C, you have the full thermal profile that materials like PEEK and PEKK require. No desktop machine in this price bracket offers this combination out of the box. Most industrial machines that do cost €50,000–€200,000. The Prusa Pro HT90 does not. Key Specifications Build volume Ø300 × 400 mm (cylindrical) Kinematics Delta Chamber temperature Up to 90°C (active, fully enclosed) Nozzle temperature Up to 500°C Print heads included 2 — High-Flow and High-Temperature (swappable, no tools) Filtration Built-in HEPA air recirculation Extruder Direct drive with load cell sensor (auto bed levelling) Resonance compensation Input Shaper Connectivity Online and offline, remote monitoring The Delta Architecture The HT90 uses delta kinematics — three arms arranged around a central column, moving a print head in a cylindrical build volume. This is worth understanding because it explains several characteristics of the machine. Delta printers tend to be faster than Cartesian printers at equivalent quality because the effector (print head) is lighter and the movement geometry allows high accelerations with less vibration. The Input Shaper resonance compensation built into the HT90 further extends this advantage — it measures and compensates for mechanical resonances in real time, allowing fast prints without ringing artefacts. The cylindrical build volume — Ø300mm diameter, 400mm tall — is particularly well suited to tall parts, round components, and anything with rotational symmetry. The 400mm height is exceptional for a machine in this class and enables large single-piece prints that would require splitting on most desktop machines. The Two Print Heads One of the HT90's most practical features is that it ships with two specialised heads that swap without tools in a few minutes: The High-Flow Head is optimised for standard and mid-range materials — PLA, PETG, ABS, ASA, PA. It prioritises throughput and surface quality. For rapid prototyping in standard materials, this is the head to use. Combined with Input Shaper, it enables very fast print speeds without visible quality loss. The High-Temperature Head is built for PEEK, PEKK, PPS, PSU, PES, and PEI (Ultem). It reaches 500°C and is constructed from materials that can withstand sustained operation at that temperature. This is not a modified standard head — it is engineered specifically for engineering polymers. The load cell sensor in the extruder system handles first layer calibration automatically at the start of every print. No manual bed levelling is required, which is particularly important when the chamber is at 90°C and you don't want to reach inside. HEPA Filtration — Why It Matters for Engineering Materials PEEK, Ultem, and similar polymers release volatile organic compounds (VOCs) and ultrafine particles when printed at high temperatures. These are not benign. Without adequate filtration, printing engineering polymers in an enclosed space represents a genuine occupational health concern. The HT90 integrates a HEPA air recirculation system directly into the machine. It is not an optional add-on or an aftermarket upgrade — it is active whenever the chamber is enclosed and printing. This makes the HT90 substantially safer to use in professional environments — offices, labs, shared workspaces — than a machine without active filtration. Who Should Buy the HT90 The HT90 is the right machine for a specific set of buyers. It is not the right machine for everyone. It is right for you if: You need to print PEEK, PEKK, PPS, PSU, or PEI (Ultem) for functional end-use parts You are prototyping medical devices that require biocompatible, autoclave-sterilisable materials You are producing automotive or aerospace components that must survive thermal cycling or sustained high temperatures You need a large build volume — Ø300 × 400mm — for single-piece industrial-scale parts You are currently paying for bureau printing in engineering materials and want to bring that capability in-house You have a research lab that needs engineering polymer capability without an industrial machine budget It is probably not right for you if: You primarily print PLA, PETG, or standard materials — a Prusa MK4S or Core One will serve you better at lower cost You need multi-material printing — the HT90 is a single-material machine per print Your highest temperature requirement is ABS or ASA — a Bambu Lab X1C or similar is a more cost-effective solution for those materials Where to Buy The Prusa Pro HT90 is available from Eolas Prints — authorised Prusa resellers based in Cantabria, Spain, serving customers across Europe. EU-compliant warranty and support included. Continue Reading Part 2: High-Temperature Filament Guide — PEEK, PEKK, PA-CF and What They Need from a Printer Part 3: Printing with the HT90 — Settings, Materials, and Practical Tips Part 4: Prusa Pro HT90 vs Industrial 3D Printers — Is It the Right Tool for Your Business?

Bambu Lab printers are the easiest FDM machines to get started with — but like all FDM printers, they benefit from proper calibration. The good news is that Bambu Studio (and OrcaSlicer, the community-developed alternative) includes built-in calibration tools that make the process far simpler than on traditional printers. No G-code commands, no manual calculations.This guide covers every calibration step in Bambu Studio in the order you should run them: from first layer setup to flow rate to pressure advance. Run through these once when you first set up a new filament, and your prints will be consistently excellent.Before You Start: Load the Correct Filament ProfileBambu Studio includes filament profiles for Eolas Prints filaments. In the Prepare tab, click the filament dropdown and search for Eolas Prints. Select your material. These profiles are pre-tuned starting points — calibration refines them further for your specific printer and environment.If you cannot find an Eolas Prints profile, use the closest generic profile (e.g. Generic PLA for our PLA 1.75mm) and calibrate from there.Step 1: First Layer CalibrationThe first layer is the foundation of every print. If it's wrong, nothing else you calibrate will fully compensate.Using the Live Z-Offset AdjustmentOn Bambu Lab printers, Z-offset is called Nozzle Offset Z and is adjusted during the first layer of a real print or a calibration print. Start a print (or the built-in first layer calibration: Calibration → First Layer Calibration in Bambu Studio). Watch the first layer deposit. The filament lines should be slightly squished onto the bed — visible as slightly flattened lines that merge together. If the lines are round and separated (like a wire sitting on top of the bed), the nozzle is too high. During printing, use the Live Adjust Z option on the printer screen or in the Bambu Handy app to move the nozzle closer or further from the bed in real time. Adjust in increments of 0.05mm. The correct Z-offset produces lines that are ~80% of their original circular width — visibly squished but not so flat that they spread excessively. What Good vs Bad First Layers Look Like Appearance Diagnosis Fix Lines are round, gaps between them Nozzle too far from bed Lower Z-offset (move nozzle closer) Lines squished flat, bleeding into each other Nozzle too close Raise Z-offset (move nozzle further) Gaps at corners, lifting edges Bed adhesion problem, not Z-offset Clean bed with IPA, check bed temperature Slightly flattened lines touching but not bleeding Correct No adjustment needed Step 2: Flow Rate CalibrationFlow rate (also called extrusion multiplier) controls how much filament is deposited per unit of movement. Even small deviations cause over- or under-extrusion that affects dimensional accuracy, surface quality, and part strength.Running the Flow Rate Calibration in Bambu Studio In Bambu Studio, go to Calibration → Flow Rate. Select your printer and filament profile. Print the calibration model. It prints a series of squares or lines at different flow rate values, labelled with the percentage offset applied. Examine the results. Look for the sample that shows the smoothest surface with no gaps (under-extrusion) and no raised ridges or excess material at corners (over-extrusion). Enter the winning percentage in your filament profile: Filament → Advanced → Flow ratio. If the default is 1.0 and the best sample was at +5%, set flow ratio to 1.05. How to Read Flow Rate Results Surface looks rough or grainy with gaps between lines: Under-extrusion — increase flow rate Surface has raised ridges, excess material at corners, or is bubbly: Over-extrusion — reduce flow rate Smooth, uniform surface with no excess material: Correct flow rate Typical correct flow rates for Eolas Prints filaments are within ±5% of 1.0. If your calibration produces a result outside this range, check for a partial clog before accepting the value.Step 3: Pressure Advance CalibrationPressure advance (called Linear Advance in Marlin firmware) compensates for the lag between the extruder motor moving and the actual change in nozzle pressure. Without it, corners tend to over-extrude as the nozzle decelerates, and the filament takes a fraction of a second to stop flowing after the move ends.Bambu Lab printers use a proprietary implementation of pressure advance that is pre-set per material — but calibrating it for your specific filament and environment improves corner sharpness and reduces blobs significantly.Running Pressure Advance Calibration in OrcaSlicerOrcaSlicer (the community-developed Bambu-compatible slicer) has the most accessible pressure advance calibration interface. If you are using Bambu Studio, the equivalent is in Calibration → Pressure Advance. Open OrcaSlicer (or Bambu Studio) and navigate to Calibration → Pressure Advance. Print the calibration pattern. It produces a series of lines or a tower printed at varying pressure advance values. Look for the line or segment with the sharpest corners and smoothest surface. Sharp, clean corners with no blobs indicate the correct value. Enter the value in your filament profile: Filament → Advanced → Pressure advance. Typical Pressure Advance Values by Material Material Typical range Notes PLA 0.02 – 0.06 Standard starting point: 0.04 High Speed PLA 0.01 – 0.04 Lower than standard PLA due to formulation PETG 0.04 – 0.08 More viscous than PLA; higher PA value TPU 93A 0.1 – 0.2 Flexible filament requires significantly higher PA ABS 0.03 – 0.06 Similar to PLA ASA 0.03 – 0.07 Similar to ABS Step 4: Temperature CalibrationUnlike traditional printers where temperature towers require manual G-code editing, Bambu Studio and OrcaSlicer automate this entirely. Go to Calibration → Temperature. Set the temperature range to test. For PLA: 190–220°C. For PETG: 225–245°C. For ABS: 230–250°C. Print the temperature tower. Each section prints at a different temperature, labelled on the part. Examine: look for the section with the best bridging, sharpest overhangs, and smoothest surface without stringing. Set that temperature as the default in your filament profile. The Eolas Prints filament profiles in Bambu Studio already include optimised temperature ranges. Temperature calibration is most useful when you're using a custom or generic profile, or when trying to push maximum speed.Step 5: Max Volumetric SpeedMaximum volumetric speed (MVS) is the real limit of how fast your printer can extrude — more useful than print speed in mm/s, which ignores nozzle diameter and layer height.If you push print speed beyond your MVS, the result is under-extrusion: gaps, weak layers, and poor surface quality even though the head is moving fast. In OrcaSlicer, go to Calibration → Max Volumetric Speed. Print the calibration model. It prints at progressively faster volumetric speeds until under-extrusion appears. Find the point where quality degrades and set your filament profile's MVS to 90% of that value for reliable printing. Typical MVS values by material (0.4mm nozzle) Material Typical MVS PLA (standard) 12–18 mm³/s High Speed PLA 20–30 mm³/s PETG 8–14 mm³/s TPU 93A 2–5 mm³/s ABS 10–16 mm³/s ASA 8–14 mm³/s Step 6: Input Shaping (Resonance Compensation)Input shaping compensates for the mechanical resonance of the printer frame — the vibrations caused when the print head changes direction rapidly. Without it, fast prints show ghosting: wave-like artefacts on the surface adjacent to features like holes and walls.Bambu Lab printers run input shaping calibration automatically as part of their startup routine. You do not need to run this manually unless you notice ghosting after a hardware change (e.g. replacing the carbon rods, adding a camera, or modifying the AMS).To re-run: on the printer touchscreen, go to Settings → Calibration → Vibration Compensation and run the calibration. The printer will run a series of short test moves and update its compensation parameters automatically.Step 7: Save Your Calibrated ProfileOnce calibrated, save everything as a named filament preset so you don't need to redo it each session. In Bambu Studio or OrcaSlicer, open your filament profile. Set the calibrated values: temperature, flow rate, pressure advance, MVS. Click Save as and name it descriptively — e.g. "Eolas PLA 1.75mm Black — Calibrated" or "Eolas PETG — P1S Calibrated". This preset will appear in your filament dropdown for all future prints on this material. Calibration Order Summary Step What it fixes When to run 1. First Layer / Z-Offset Bed adhesion, elephant foot, gaps in first layer Every new printer setup, any bed change 2. Flow Rate Dimensional accuracy, surface quality, strength Each new filament type or brand 3. Pressure Advance Corner blobs, stringing, ghosting Each new filament, after speed changes 4. Temperature Tower Layer adhesion, stringing, surface quality New filament profiles or generic profiles 5. Max Volumetric Speed Under-extrusion at high speeds When pushing speed limits 6. Input Shaping Ghosting / ringing artefacts After hardware changes only (auto on startup) Related guides: Temperature Tower | Flow Test | Retraction Test | Extruder CalibrationUsing Eolas Prints filaments? All our filaments are available as named profiles in Bambu Studio. Search Eolas Prints in the filament selector. If you need help dialling in settings for a specific material, contact our technical support team.

Calibrating the extruder is a crucial aspect of 3D printing with filament (FDM or FFF). If the extruder distributes too little material, the object will have holes or walls that are too delicate. On the other hand, if it dispenses too much material, it will create an issue called over-extrusion which will leave the piece with globs and strings, aka "Stringing".

The aim of the retraction test is to achieve a "cleaner" part without material residues in the movement areas of the hotend. The slicer parameters that influence this test are mainly speed and retraction distance.

This test should be carried out every time you print with a new material, as it provides one of the main printing parameter parameter of the filament i.e. the extrusion temperature. This test consists of a staggered part, in which the extrusion temperature will be varied progressively by 5 degrees. As each material has an optimum temperature, this test has different parts for different materials. These parts are practically the same, only the temperature range is different for an easier reading.

The purpose of this test is to adjust the amount of extruded plastic, that is to say, that the deposited material is the one we want at any given moment. It is performed to correct small variations in the diameter of the filament. The parameter that influences the flow is the so-called extrusion multiplier, with a calibration of this parameter you can solve the typical problems of under-extrusion or over-extrusion.